Following the common law system introduced into Hong Kong when it became a Crown colony, Hong Kong's criminal procedural law and the underlying principles are very similar to the one in the UK. Like other common law jurisdictions, Hong Kong follows the principle of presumption of innocence. This principle penetrates the whole system of Hong Kong's criminal procedure and criminal law. Viscount Sankey once described this principle as a 'golden thread'. Therefore, knowing this principle is vital for understanding the criminal procedures practised in Hong Kong. Principle of presumption of innocence and its extended rights Apart from case law, Hong Kong also enacted a series of statutes to ensure the principle of presumption of innocence and its extended rights promptly implanted and recognised by the government and the society. Prosecution Right to institute criminal prosecution There is not a rule or law explicitly saying that the absolute right to institute a criminal prosecution is given to the Government. Thus, theoretically, the general public or individuals are allowed to prosecute. Moreover, Section 14 of the Magistrates Ordinance (i.e. Chapter 227) gives guidance on how the Secretary for Justice intervenes and assumes a private criminal prosecution. This provision indeed indirectly points out the possibility of private criminal prosecution. However, practically, private criminal prosecution does not exist because of the expensive costs involved in criminal prosecutions, the lack of manpower, resources, and special statutory powers to carry out a thorough investigation, the exclusive right for the Secretary for Justice to get involved or even take over private criminal prosecutions, the requirement of beyond reasonable doubt of evidence, etc. Consequently, the Secretary is the only one who institutes almost all the criminal prosecutions in Hong Kong. In fact, the Secretary who is the head of the Department of Justice is the person who has the sole power to control all criminal prosecutions independently. The Basic Law, Article 63, describes: Decision to prosecute Two questions Before instituting a criminal prosecution, the Secretary or the prosecutor must first address two questions: Is the evidence sufficient to justify the institution or continuation of proceedings? If it is, does the public interest require a prosecution to be pursued? Discretionary power Criminal Procedure Ordinance Section 15(1) states Therefore, the Secretary has discretionary power in determining whether or not to prosecute and is not required to prosecute in every single case. A good example is the well-known controversy involving the